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The basis of the structural-functional study of selected enzymes from the 4-alkyl- L-proline pathway
Zachovalová, Veronika ; Zdvořáková, Lucie (advisor) ; Košek, Dalibor (referee)
4-alkyl-L-proline derivate (APD) is building block of some important, bioactive specialized metabolites produced by Actinobacteria. It is found, for example, in the structure of lincosamide antibiotic lincomycin, bacterial hormone hormaomycin having antimicrobial activity, the antituberculosis compound griselimycin and pyrrolo-1,4-benzodiazepins (PBD) which have anticancer effects. APDs, or their precursors, are formed from L-leucine or L-tyrosin in a unique biosynthetic pathway consisting of up to six homologous proteins named Apd1 - Apd6. The first part of this thesis lays the foundation for a crystallization study of SAM-dependent methyltransferase Apd3 from the biosynthesis of lincomycin - the protein LmbW, in order to elucidate the identity of its natural substrate, which remains up to date a subject of scientific discussions. A purification method providing LmbW protein of sufficient quantity, quality and purity for crystallization was optimized. Subsequently the crystallization conditions allowing crystal growth were defined. The second part of the thesis deals with the elucidation of molecular basis of different reaction specificity of homologous F420H2-dependent oxidoreductases, Apd6. They catalyse reduction of identical substrate with two conjugated double bonds, however, some of them...
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The role of F420-dependent oxidoreductases in actinobacteria
Kekrt, Lukáš ; Kameník, Zdeněk (advisor) ; Palyzová, Andrea (referee)
Deazaflavin F420 is an unusual cofactor involved in oxidoreduction reactions in the cells of some microorganisms. The role of F420/F420H2-dependent oxidoreductases has been extensively described in the case of central archaeal metabolism, particularly those of methanogens. In contrast, our knowledge of these enzymes in actinobacteria is limited. This work focuses on the characterization of selected actinobacterial oxidoreductases from luciferase-like hydride transferase family, which putatively use the F420 cofactor. Specifically, Apd6 biosynthetic proteins and their sequence homologs were studied. Three recombinant proteins were prepared and purified and their enzymatic activity was tested in the presence of F420 and a set of putative substrates by means of in vitro reactions. The reaction products were monitored by liquid chromatography with UV and mass spectrometry detection. Some of the expected reaction products were detected in in vitro reactions, confirming that the proteins were catalytically active. Furthermore, one of the proteins surprisingly exhibited an unusual reaction specificity. Key words: Specialized metabolism, actinobacteria, F420 cofactor, redox reactions, reaction specificity, 4-alkyl-L-proline derivates.
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